Purpose: This study aims to measure the distance between the common site of Achilles tendon rupture and calcaneal insertion through ultrasound and to compare the outcomes between proximal and distal rupture groups. Methods: We investigated the electronic medical records of 117 patients and preoperative ultrasound describing the rupture site. Among 88 patients, we compared the patient-reported outcome and re-rupture rate of proximal and distal rupture groups. Results: The mean rupture site of the 117 included subjects was 4.5 ± 1.3 cm. The rupture site had a weak negative correlation with body mass index ( ρ = −0.230, P = 0.013). Furthermore, 77% of the patients with distal rupture reported good outcome (Achilles Tendon Rupture Score > 80) compared to 56% of the patients with proximal rupture ( P = 0.041). Conclusion: Patients with proximal rupture had less satisfactory postoperative outcomes than those with distal rupture.

Objective To reflect the potential epidemiological characteristics of Achilles tendon (AT) rupture in Shanghai, China, which has been rarely reported before. Methods This work is a descriptive epidemiology study. A total of 302 cases of AT rupture admitted to our department between 01/2013 and 02/2020 are analyzed according to telephone follow‐up and medical records. Male to female ratio is 10.3 and the average age is 37.5 years. The record of each case includes age, gender, Body mass index (BMI), quinolone use, corticoid exposure and related medical history/comorbidities. If the case is sports‐related (SR), details including kind of sports, intensity of exercise, exercise time before rupture, specific action that causes rupture and situation of warm‐up are collected. Two independent sample t ‐tests and Pearson chi‐square tests are used for statistical analysis. Results A total of 252 ruptures are SR. Male to female ratio is 15.6 in SR cases. Most SR ruptures occur in patients aged 25–39 years. Ball games are major sports responsible for rupture: basketball in 95 (37.7%), badminton in 68 (27.0%) and soccer in 62 (24.6%). Acceleration and running start is the specific action that cause most (37.7%) ruptures. AT cases are observed in 91 patients with warm‐up and 161 without preparation before exercise. As a result, more ruptures happened within 10 min' sports in 161 unprepared (22.4%) than in 91 prepared (5.5%) cases. In SR cases, 107 and 145 cases are observed on weekends and weekdays. Of the 302 total cases, 64 are associated with Achilles tendinopathy. Frequently reported factors such as quinolone use and corticoid exposure are found only in two and 11 of all cases, respectively. Conclusion Middle‐aged males are common victims of AT rupture in Shanghai. Sports including basketball, badminton, soccer and actions involving in sudden and severe contraction of AT cause most ruptures. Warm‐up before exercise reduces rupture in short time. Factors such as quinolone, corticoid and Achilles tendonitis still need attention.

Background This study was aimed to develop a novel dynamic measurement technique for testing the material properties and investigating the effect of continuous compression load on the structural and mechanical properties of human heel pad during actual gait. Methods The dual fluoroscopic imaging system (DFIS) and dynamic foot-ground contact pressure-test plate were used for measuring the material properties, including primary thickness, peak strain, peak stress, elastic modulus, viscous modulus and energy dissipation rate (EDR), both at time zero and following continuous loading. Ten healthy pilot subjects, aged from 23 to 72 (average: 46.5 ± 17.6), were enrolled. A “three-step gait cycle” is performed for all subjects, with the second step striking at a marked position on the force plate with the heel to maintain the location of the tested foot to be in the view of fluoroscopes. The subjects were measured at both relaxed (time-zero group) and fatigue (continuous-loading group) statuses, and the left and right heels were measured using the identical procedures. Results The peak strain, peak stress, elastic modulus, and EDR are similar before and after continuous load, while the viscous modulus was significantly decreased (median: 43.9 vs. 20.37 kPa•s; p < 0.001) as well as primary thicknesses (median: 15.99 vs. 15.72 mm; p < 0.001). Age is demonstrated to be moderately correlated with the primary thicknesses both at time zero (R = -0.507) and following continuous load (R = -0.607). The peak stress was significantly correlated with the elastic modulus before (R = 0.741) and after continuous load (R = 0.802). The peak strain was correlated with the elastic modulus before (R = -0.765) and after continuous load (R = -0.801). The correlations between the viscous modulus and peak stress/ peak strain are similar to above(R = 0.643, 0.577, − 0.586 and − 0.717 respectively). The viscous modulus is positively correlated with the elastic modulus before (R = 0.821) and after continuous load (R = 0.784). Conclusions By using dynamic fluoroscopy combined with the plantar pressure plate, the in vivo viscoelastic properties and other data of the heel pad in the actual gait can be obtained. Age was negatively correlated with the primary thickness of heel pad and peak strain, and was positively correlated with viscous modulus. Repetitive loading could decrease the primary thickness of heel pad and viscous modulus.